The present invention is concerned with the vulcanization of mineral-loaded chlorobutyl rubber. Chlorobutyl rubber possesses many desirable properties including exceptionally good air permeability, flex properties, oxygen properties and good heat resistance. The commercial success of chlorobutyl rubber is largely dependent on its application in products such as tire innerliners and side walls, conveyor or power transmission belting, hoses and wire insulation. In many of these applications the chlorobutyl rubber is mineral-loaded to further enhance the product's properties and/or lower the cost of manufacture.
Mineral-loaded chlorobutyl compounds are difficult to cure in the presence of steam. It is believed that the hydroscopic nature of the fillers cause absorption of the moisture from the steam and thus interferes with crosslinking. Unfortunately, conventional cure systems, typically employed with carbon black and dry cured mineral-loaded compounds, are ineffective for open steam curing of chlorobutyl rubber. Therefore, there exists a need for an improved curing system.